The correct option is B A- Gibberellins, B-Abscisic acid
Gibberellins are plant growth substances that promote bolting (the process of development of a flowering shoot prior to the reproductive phase) in beet, cabbage, and other plants with rosette habitat.
They are used for the elongation of stem and to increase the internodal length in plants. They also mobilize food reserves in germinating seeds and are influential in inducing flowering and fruit development.
Abscisic acid (ABA) is a plant growth inhibitor and plays a vital role in inhibiting plant metabolism and seed germination. It triggers the closing of stomata and raises the endurance of plants to different sorts of stresses. Hence, it is also termed as the stress hormone.
ABA performs an essential function in seed growth, maturation, and dormancy. Through producing dormancy, ABA supports seeds to resist desiccation and other factors unsuitable for development. Under most circumstances, ABA functions as an antagonist to gibberellins.
Ethylene is a gaseous plant growth regulator. It influences the horizontal growth of the seedling, swelling of the axis, apical hook formation etc. It inhibits stem elongation and breaks seed and bud dormancy. It initiates germination in pea nut seeds and potato tubers.